Fix contract typo in documentation

brag/brag/brag.scrbl

@@ -117,7 +117,7 @@ That's @racket[(some [pig])], essentially.
 What happens if we pass our @racket[parse] function a bigger source of tokens?
 
 @interaction[#:eval my-eval
-             @code:comment{tokenize: string -> (sequenceof token-struct?)}
+             @code:comment{tokenize: string -> (sequence/c token-struct?)}
              @code:comment{Generate tokens from a string:}
              (define (tokenize s)
                (for/list ([str (regexp-match* #px"\\(|\\)|\\w+" s)])
@@ -689,8 +689,8 @@ continues till the end of the line.
 A @deftech{multiline comment} begins with @litchar{(*} and ends with @litchar{*)}.
 
 An @deftech{identifier} is a sequence of letters, numbers, or
-characters in the set @racket["-.!$%&/<=>^_~@"]. It must not contain
+characters in the set @racket["-.!$%&/<=>?^_~@"]. It must not contain
-@litchar{*}, @litchar{+}, @litchar{?}, or @litchar|{{}| and @litchar|{}}|, as those characters are used to denote quantification.
+@litchar{*}, @litchar{+}, or @litchar|{{}| and @litchar|{}}|, as those characters are used to denote quantification.
 
 A @deftech{pattern} is one of the following:
 @itemize[
@@ -922,7 +922,7 @@ A program written in @litchar{#lang brag} produces a module that provides a few
 bindings. The most important of these is @racket[parse]:
 
 @defproc[(parse [source-path any/c #f] 
-                [token-source (or/c (sequenceof token)
+                [token-source (or/c (sequence/c token)
                                     (-> token))])
          syntax?]{